1. Field of the Invention
This invention relates generally to a device placed in a sewer pipe to trap certain articles which may plug the pipe. In particular, this invention relates to a guard with self-cleaning features having special applications for toilets in prisons and other correctional or industrial facilities.
2. Prior Art
The desirability of providing a guard in a drain pipe or sewer pipe to trap articles which would otherwise clog the pipe has long been recognized in the prior art. With regard to a sewer pipe leading from a toilet, the requirement of a guard is that the ordinary solids introduced into a toilet, such as excrement and tissue paper, should be allowed to pass unobstructed, while articles not readily decomposed, such as cloth, diapers, sanitary napkins and plastic, should be trapped. The aforementioned requirements are particularly stringent in the prison setting. Prisoners are prone to introduce cloth and paper into the toilets with the intent that the prison sewage discharge lines become clogged and the sewage water back up so as to overflow into the prisoners' cells. With an ordinary sewage system it is not possible in many cases to determine which prisoner caused the sewage line to become clogged. Thus it is not always possible to punish the prisoner thereby deterring similar future episodes.
Especially damaging is cloth or other material which, even if it does not clog the pipes, is not broken down and passes to the treatment plant where the material can not be digested or properly handled, which can cause such treatment plant to be shut down.
Another problem particular to the prison setting is the need to prevent various metal objects from being flushed through the prison sewage system. In many instances these metal objects will be homemade knives and other weapons that the prisoner is trying to dispose of in order to avoid being caught in possession of these prohibited devices.
Yet another problem with the current art is that it cannot be inserted into pipes with curves or angles, limiting implementations to those applications with only straight pipes.
Still another problem is that the device must be opened in order to inspect the contents of each line. This can often be a tedious, time-consuming, and potentially messy process.
Various stationary devices have been employed in sewer lines to trap undesirable articles. Several of these inventions disclose devices with hooks which are positioned in the sewer line. However, because these devices are stationary, there is a tendency for otherwise safe waste, especially toilet paper, to accumulate on the hooks. Eventually, the line plugs at the site of the guard device.
Devices which rotate within a pipe to scrape the interior of the pipe or pulverize solids have been employed with some success. In a prison setting, however, where material and garments are introduced into the sewage system, additional burdens are placed upon the comminuting devices. For example, even the most powerful in-line device disclosed in the prior art would have difficulty pulverizing a bed sheet. In addition they would not be able to prevent the passage of certain metal objects that are commonly made by prisoners and used as weapons. However, most importantly, these devices are used after the incident has occurred in order to clear a line, which, without the current device, may occur at any number of places in the sewer or drainage system. The current device permits the stoppage to be planned for, by placing the invention where the stoppage can be best dealt with, generally, before if affects other areas of the facility, or worse still, other portions of the system or processing facility.
Further, none of the current art provides a way to inspect the contents of the line without opening the line, nor do they permit the installation of the line guard in a pipe that is curved or angled.